This schematic diagram represents a power management circuit built around the SY3408 IC. The SY3408 is a boost converter IC commonly utilized in power bank circuits, versatile charging solutions, and the Earbuds Case Charging Circuit. Let’s go through the components and their pin connections. Discover the SY3408 IC with a detailed schematic diagram, datasheet, pinout, Repair Ways, and connection wiring. Learn how this IC works and its applications.
Main Components and Connections
SY3408 IC Pin Layout
LX (Pin 1): This is the switching pin connected to the inductor L1 (2.2µH). It drives the inductor to store and transfer energy.
GND (Pin 2): Ground connection.
BAT (Pin 3): This pin is associated with the battery input, where the circuit draws power from a battery. The BAT pin is tied to the battery's positive terminal.
VIN (Pin 4): The input voltage from the USB control source is provided to this stick through the C1 (1µF) capacitor.
KEY (Pin 5): This pin is connected to a switch S1 and a resistor R1 (15kΩ). When the switch is squeezed, the yield (VOUT) is enabled.
VOUT (Pin 6): This output voltage pin conveys the circuit's boosted voltage to charge external devices. A C2 (10µF) capacitor is connected between VOUT and ground to stabilize the output voltage.
D+ (Pin 7): This pin is utilized for data communication between the power bank and the connected device (to indicate charging protocols).
Inductor (L1 - 2.2µH)
Connected between VIN and LX. It is responsible for energy capacity during the boost operation.
Capacitors
C1 (1µF): Connected between VIN and GND. This capacitor smooths out any input voltage ripples.
C2 (10µF): Connected between VOUT and GND to stabilize the yield voltage.
C3 (1µF): Another input capacitor connected across VIN to provide extra filtering.
LED Indicators:
DLED1 and DLED2 are two LEDs utilized to indicate the charging status. They are connected between VOUT and GND and between BAT and GND, respectively, through S1.
Switch (S1):
The switch is connected to the KEY stick to actuate or deactivate the circuit output. When squeezed, the circuit allows the boosted yield voltage to show up at VOUT.
Resistor (R1 - 15kΩ):
It is connected in series with the switch S1 and the KEY pin to ensure proper voltage activating when the switch is pressed.
How It Works
Power Input: The circuit takes input from a battery connected to the BAT stick and a USB input associated with the VIN pin.
Boost Transformation: The SY3408 boosts the battery voltage via the inductor L1 and delivers the boosted yield voltage to the VOUT pin.
Key Control: The KEY stick controls the output through the switch S1. When S1 is squeezed, it closes the circuit and allows the boosted output voltage to show up at VOUT.
LED Sign: The LEDs (DLED1 and DLED2) appear the power status or charging status. One Driven shows when the circuit is fueled from VIN, and the other Driven indicates when it's fueled by the battery.
Filtering: The capacitors C1, C2, and C3 smooth out the input and output voltage to minimize swells and stabilize the output.
Summary of Pin-to-Pin Connections
LX → L1 (2.2µH inductor) → Input voltage (VIN).
BAT → Battery positive terminal.
VIN → USB input voltage (through C1).
KEY → Connected to S1 switch (to control VOUT).
VOUT → Output voltage (through C2).
D+ → Data communication pin to a device for charging control.
FAQs
What is the main function of the SY3408 IC?
The SY3408 IC is a boost converter that increases the voltage from a battery to power external devices, commonly used in power banks and charging solutions.
How does the circuit control the output voltage?
The output voltage is controlled by a switch (S1) connected to the KEY pin. When the switch is squeezed, it closes the circuit and enables the boosted output voltage at the VOUT pin.
What role do the capacitors (C1, C2, C3) play in the circuit?
The capacitors smooth out input and output voltage ripples, minimizing fluctuations and stabilizing the output voltage to ensure consistent performance.
What are the purposes of the LEDs (DLED1 and DLED2) in the circuit?
The LEDs indicate the charging status of the circuit, with one LED showing when the circuit is powered from the USB input (VIN) and the other indicating when it's powered by the battery.
What is the significance of the inductor (L1) in the boost converter circuit?
The inductor (L1) stores energy during the boost operation and releases it to increase the voltage, playing a crucial role in the conversion process from the lower battery voltage to the higher output voltage.